A low cost and green curcumin/ZnO nanocomposites: Preparation, characterization and photocatalytic aspects in removal of amaranth dye and hydrogen evolution generation

Curcumin is natural non-toxic yellow pigment with potent biological and chemical reactivity due to the existence of keto-enol chemical structure. Incorporation of curcumin on ZnO surface enhances the absorbability of visible light radiations and increases the redox power of the charge carriers, In this research, curcumin/ZnO nanoparticles are generated for efficient decomposition of anionic amaranth dye and production of hydrogen gas as renewable fuel resource. ZnO nanoparticles were synthesized through sol-gel concepts by controlled hydrolysis of zinc acetylacetonate in presence of pluronic template. Curcumin with various concentration [1-5] wt% are deposited on ZnO nanoparticles in ultrasonic bath of 200 W intensity. The solid specimens are well explored by XRD, adsorption isotherms of nitrogen at 77K, HRTEM, XPS, DRS and PL. Curcumin molecules are interacted chemically with ZnO nanoparticles through interfacial charge transfer complex that improves the visible light harvesting and enhances the efficiency of the charge carriers separation. In solar reactor, ZnO with 3 wt % curcumin decomposes 95% of amaranth dye and produce hydrogen gas with evolution rate 5.1 mmolg(-1)hr(- 1). Depend on step S-scheme charge migration route, the positive hole and negative electrons in the valence band and LUMO energy level of ZnO and curcumin, respectively exerts a strong oxidative and reductive efficiency for the photocatalytic processes. The trapping experiments reveal that superoxide, positive holes and hydroxyl radicals are generated for rapid decomposition of amaranth dye. The durability and high photocatalytic performance of this novel nanocomposites can be used in various industrial and environmental purposes.